You have to install Ruby like a program. You can download it from the Ruby website. From there, you can use another program to help write code; I haven't tried Ruby in Eclipse but it handles Java well. I use NetBeans for Ruby.

I know this is kinda strange, and IDK if it's coincidental, but I was idly browsing the forums and noticed something about a "thief" named MeFan. And your meteorite name is MeFan3... I'm not trying to accuse you or anything, but I was just wondering if it was you.